The present invention relates to a novel carbapenem compound and a pharmaceutically acceptable salt thereof, which are useful as agents for the prophylaxis and treatment of bacterial infectious diseases. More particularly, the present invention relates to a novel carbapenem compound and a pharmaceutically acceptable salt thereof, which have sufficient antibacterial activity and which permit oral absorption; an oral antibacterial agent containing said compound as an active ingredient; and an intermediate compound for the production of said carbapenem compound and a salt thereof.
Many compounds having a carbapenem skeleton have been found as agents for treating infectious diseases, from which some carbapenem compounds having superior antibacterial activity have been put to practical use or under development for practical application. For example, a carbapenem compound of the formula (A) 
has been put to practical use and used in the clinical situations. This carbapenem compound has a broad antibacterial spectrum and potent antibacterial activity, and is free of instability to renal dehydropeptidase, which has been considered to be a drawback of conventional carbapenem compounds. It is a superior characteristic of this compound that it can be administered solely without using a stabilizer.
However, these carbapenem compounds show poor absorption from the digestive tract, which limits their clinical administration route to injection alone. An oral agent is easy and convenient to administer as compared to injections, and highly utilizable in clinical situations. Thus, there is a need for the development of a carbapenem compound for oral administration, which has potent antibacterial activity and broad antibacterial spectrum, and which shows superior absorption from the digestive tract.
It is therefore an object of the present invention to provide a carbapenem compound which has superior antibacterial activity and which shows superior absorption from the digestive tract.
Another object of the present invention is to provide use of said carbapenem compound.
A yet further object of the present invention is to provide an intermediate suitable for the production of said carbapenem compound.
The present inventors have conducted intensive studies in an attempt to achieve the above-mentioned objects, and found that a novel carbapenem compound of the following formula (I) and a pharmaceutically acceptable salt thereof show superior absorption from the digestive tract, have sufficiently potent antibacterial activity and are extremely useful as oral antibacterial agents. Further, the present inventors have found a novel intermediate compound usable for the production of said compound, which resulted in the completion of the present invention.
Accordingly, the present invention provides the following.
(1) A carbapenem compound (I) of the formula (I) 
wherein
R1 and R2 may be the same or different and each is a modifying group hydrolyzable in the body;
R3 and R4 may be the same or different and each is a lower alkyl; or
R3 and R4 form a cyclic amino together with the adjacent nitrogen atom, and a pharmaceutically acceptable salt thereof.
(2) The carbapenem compound of (1) above, wherein R1 and R2 may be the same or different and each is a modifying group hydrolyzable in the body, and R3 and R4 may be the same or different and each is a lower alkyl, and a pharmaceutically acceptable salt thereof.
(3) The carbapenem compound of (1) above, wherein R2 is 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl and R3 and R4 are each methyl, and a pharmaceutical acceptable salt thereof.
(4) The carbapenem compound of (1) above, wherein R1 is pivaloyloxymethyl and R2 is 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl, and a pharmaceutically acceptable salt thereof.
(5) The carbapenem compound of (1) above, wherein R1 and R2 are each pivaloyloxymethyl, and a pharmaceutically acceptable salt thereof.
(6) The carbapenem compound of (1) above, which is selected from the group consisting of
pivaloyloxymethyl (1R,5S,6S)-2-}(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate hydrochloride,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-diethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio }-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-methylethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio }-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-pyrrolidinylcarbonyl)-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-piperidinylcarbonyl)-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate, and
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-azetidinylcarbonyl)-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate, and a pharmaceutically acceptable salt thereof.
(7) An antibacterial agent comprising the carbapenem compound of (1) above, which is represented by the formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.
(8) The antibacterial agent of (7) above, which is for oral administration.
(9) A carbapenem compound of the formula (II) 
wherein
R2 is a modifying group hydrolyzable in the body;
R3 and R4 may be the same or different and each is a lower alkyl; or
R3 and R4 form a cyclic amino together with the adjacent nitrogen atom; and
R5 is a hydrogen atom or a carboxyl-protecting group, and a salt thereof.
(10) The carbapenem compound of (9) above, which is selected from the group consisting of
p-nitrobenzyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate and
sodium (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
and a salt thereof.
The modifying group hydrolyzable in the body at R1 and R2 is preferably hydrolyzed in intestine or blood, and is exemplified by optionally substituted aryl (e.g., phenyl, tolyl, xylyl, indanyl and the like), 1-alkanoyloxyalkyl, 1-alkoxycarbonyloxyalkyl, phthalidyl, 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl and the like. Particularly, 1-alkanoyloxyalkyl, 1-alkoxycarbonyloxyalkyl and 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl are preferable.
The optionally substituted aryl is preferably non-substituted or substituted by 1 to 3 substituents which may be the same or different. Examples of the substituent include alkyl having 1 to 4 carbon atoms such as methyl, ethyl and the like.
The number of the carbon atoms of the alkanoyl moiety of 1-alkanoyloxyalkyl is preferably 2 to 10, more preferably 2 to 7, and it may be linear, branched or cyclic. The number of the carbon atom of the alkyl moiety is preferably 1 to 3, more preferably 1 or 2.
Examples of 1-alkanoyloxyalkyl include acetoxymethyl, propionyloxymethyl, n-butyryloxymethyl, isobutyryloxymethyl, pivaloyloxymethyl, n-valeryloxymethyl, 2-methylbutyryloxymethyl, isovaleryloxymethyl, n-hexanoyloxymethyl, 3-methylvaleryloxymethyl, neohexanoyloxymethyl, 2-methylhexanoyloxymethyl, 2,2-dimethylvaleryloxymethyl, neoheptanoyloxymethyl, cyclohexanecarbonyloxymethyl, cyclohexylacetoxymethyl, 1-acetoxyethyl, 1-propionyloxyethyl, 1-n-butyryloxyethyl, 1-isobutyryloxyethyl, 1-n-valeryloxyethyl, 1-pivaloyloxyethyl, 1-isovaleryloxyethyl, 1-n-hexanoyloxyethyl, 1-cyclohexanecarbonyloxyethyl and the like.
The number of the carbon atom of the alkoxy moity of 1-alkoxycarbonyloxyalkyl is preferably 1 to 10, more preferably 1 to 7, and it may be linear, branched or cyclic. The number of the carbon atom of the alkyl moiety is preferably 1 to 3, more preferably 1 or 2.
The 1-alkoxycarbonyloxyalkyl is exemplified by 1-methoxycarbonyloxyethyl, 1-ethoxycarbonyloxyethyl, 1-n-propoxycarbonyloxyethyl, 1-isopropoxycarbonyloxyethyl, 1-n-butoxycarbonyloxyethyl, 1-secbutoxycarbonyloxyethyl, 1-t-butoxycarbonyloxyethyl, 1-pentyloxycarbonyloxyethyl and 1-cyclohexyloxycarbonyloxyethyl.
The lower alkyl at R3 and R4 is a linear or branched alkyl having 1 to 6 carbon atoms, which is exemplified by methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, isohexyl, neohexyl and the like. Particularly, methyl, ethyl, propyl and butyl are preferable.
The cyclic amino formed by R3 and R4 together with the adjacent nitrogen atom is a 4- to 6-membered cyclic amino. Examples of the above-mentioned cyclic amino include azetidinyl, pyrrolidinyl, piperidinyl and the like.
The carboxyl-protecting group at R5 include, for example, t-butyl, t-amyl, benzyl, p-nitrobenzyl, p-methoxybenzyl, diphenylmethyl, p-nitrophenyl, methoxymethyl, ethoxymethyl, benzyloxymethyl, methylthiomethyl, trityl, 2,2,2-trichloroethyl, trimethylsilyl, diphenylmethoxybenzenesulfonylmethyl, dimethylaminoethyl and the like. Of these, p-nitrobenzyl, p-methoxybenzyl and diphenylmethyl are particularly preferable.
The carbapenem compound (I) and carbapenem compound (II) may form pharmaceutically acceptable salts.
Inasmuch as carbapenem compound (I) and carbapenem compound (II) have a basic group, they can form acid addition salts. The acid used for forming such acid addition salt is subject to no particular limitation as long as it is pharmaceutically acceptable. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, organic acids such as oxalic acid, fumaric acid, maleic acid, citric acid, tartaric acid and methanesulfonic acid, and the like.
When carbapenem compound (II) has a carboxyl group (i.e., when R5 is a hydrogen atom), a salt can be formed at said carboxyl group. Examples of the salt at carboxyl group include alkali metal salts (e.g., sodium salt, potassium salt and the like), alkaline earth metal salts (e.g., calcium salt, magnesium salt and the like), organic base salts (e.g., triethylamine salt, dicyclohexylamine salt, pyridine salt and the like), and the like.
The preferable examples of the carbapenem compound (I) and carbapenem compound (II) are the following:
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-pivaloyloxyethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio }-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-acetoxyethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-isopropoxycarbonyloxyethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylamino-carbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-ethoxycarbonyloxyethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylamino-carbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-cyclohexyloxycarbonyloxyethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethyl-aminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
p-nitrobenzyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxy-ethyl]-1-methylcarbapen-2-em-3-carboxylate,
diphenylmethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
p-methoxybenzyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
(1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylic acid,
pivaloyloxymethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylamninocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methyl-carbapen-2-em-3-carboxylate,
1-pivaloyloxyethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methyl-carbapen-2-em-3-carboxylate,
1-acetoxyethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylarninocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methyl-carbapen-2-em-3-carboxylate
1-isopropoxycarbonyloxyethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylamino-carbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-ethoxycarbonyloxyethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylamino-carbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
1-cyclohexyloxycarbonyloxyethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl-(1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
p-nitrobenzyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylarninocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methyl-carbapen-2-em-3-carboxylate,
diphenylmethyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methyl-carbapen-2-em-3-carboxylate,
p-methoxybenzyl (1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-1-methyl-carbapen-2-em-3-carboxylate,
(1R,5S,6S)-2-[(3S,5S)-(5-N,N-dimethylaminocarbonyl-1-pivaloyloxymethyl)-pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylic acid,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-dimethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate hydrochloride,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-diethylaminocarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxy-ethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-N,N-methylethylaminocarbonyl-1-(5-methy-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-pyrrolidinylcarbonyl)-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio }-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate,
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-piperidinylcarbonyl)-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate, and
pivaloyloxymethyl (1R,5S,6S)-2-{(3S,5S)-[5-(1-azetidinylcarbonyl-1-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl]pyrrolidin-3-ylthio}-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate, and the like.
The carbapenem compound (I) and a pharmaceutically acceptable salt thereof, and carbapenem compound (II) and a pharmaceutically acceptable salt thereof can be produced by any of the following production methods 1 to 4. 
wherein R1, R2, R3 and R4 are as defined above, and X is a leaving group such as a halogen atom (e.g., chlorine, bromine and iodine), alkanesulfonyloxy (e.g., methanesulfonyloxy, ethanesulfonyloxy, propanesulfonyloxy and butanesulfonyloxy), arylsulfonyloxy (e.g., phenylsulfonyloxy and tolylsulfonyloxy), and the like.
Compound (I) can be obtained by dissolving compound (IIa) (compound of formula (II) wherein R5 is hydrogen atom) in a solvent which does not interfere with the reaction (e.g., dioxane, acetonitrile, tetrahydrofuran, chloroform, methylene chloride, ethylene chloride, benzene, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and mixtures thereof), and reacting the compound with about 1-5 times, preferably about 1-2 times, the molar amount of compound (III) in the presence of a base.
The base to be used is subject to no particular limitation, but it is preferably an inorganic base such as sodium hydrogencarbonate, potassium carbonate and the like, an organic base such as triethylamine and diisopropylethylamine, and the like.
The reaction temperature is not particularly limited, but the reaction is preferably carried out at a relatively low temperature to suppress side reaction, which is generally xe2x88x9230-40xc2x0 C., preferably xe2x88x9220-0xc2x0C. While the reaction time varies depending mainly on reaction temperature, the kind of reaction reagents and the like, it is generally from 30 minutes to a dozen hours or so.
Where necessary, compound (IIa) can be introduced into a reactive derivative thereof such as alkali metal salt (e.g., sodium salt, potassium salt and the like), alkaline earth metal salt (e.g., calcium salt), triethylamine salt, dicyclohexylamine salt, pyridine salt, and the like, and reacted with compound (III). 
wherein R1, R2, R3, R4 and X are as defined above.
Compound (I) can be obtained by dissolving compound (IV) in a solvent which does not interfere with the reaction (e.g., dioxane, acetonitrile, tetrahydrofuran, chloroform, methylene chloride, ethylene chloride, benzene, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and mixtures thereof), and reacting the compound with about 1 5 times, preferably about 1 2 times, the molar amount of compound (V). Compound (IV) can be obtained by reacting the carboxylic acid disclosed in Japanese Pat. Unexamined Publication No. 233076/1985 and the like, and compound (III), in the same manner as in Production Method 1.
This reaction can be also carried out in the presence of a base. The base to be used is subject to no particular limitation, but it is preferably an inorganic base, such as sodium hydrogencarbonate, potassium carbonate and the like, or an organic base, such as triethylamine, diisopropylethylamine and the like.
The reaction temperature is not particularly limited, but the reaction is preferably carried out at a relatively low temperature to suppress side reaction, which is generally xe2x88x9230-40xc2x0 C., preferably xe2x88x9220-0xc2x0 C. While the reaction time varies depending mainly on reaction temperature, the kind of reaction reagents and the like, it is generally from 30 minutes to a dozen hours or so. 
wherein R2, R3, R4 and R5 are as defmed above and R6 is alkanesulfonyl, such as methanesulfonyl, ethanesulfonyl, propanesulfonyl, butanesulfonyl and the like, arylsulfonyl, such as phenylsulfonyl, tolylsulfonyl and the like, dialkylphosphoryl, such as dimethylphosphoryl, diethylphosphoryl, diisopropylphosphoryl, dibutylphosphoryl and the like, or diarylphosphoryl, such as diphenylphosphoryl, ditolylphosphoryl and the like.
Compound (II) can be obtained by dissolving compound (VI) disclosed in Japanese Patent Unexamined Publication No. 12676/1996 and the like in a solvent which does not interfere with the reaction (e.g., dioxane, acetonitrile, tetrahydrofuran, chloroform, methylene chloride, ethylene chloride, benzene, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and mixtures thereof), and reacting the compound with about 1-5 times, preferably about 1-3 times, the molar amount of mercapto compound (VII) in the presence of a base.
The base to be used is subject to no particular limitation, but it is preferably an inorganic base, such as sodium hydrogencarbonate, potassium carbonate and the like, or an organic base, such as triethylamine, diisopropylethylamine and the like.
The reaction temperature is not particularly limited, but the reaction is preferably carried out at a relatively low temperature to suppress side reaction, which is generally xe2x88x9230-40xc2x0 C., preferably xe2x88x9220-0xc2x0 C. While the reaction time varies depending mainly on reaction temperature, the kind of reaction reagents and the like, it is generally from 30 minutes to a dozen hours or so.
The starting compound (VII) for the synthesis of compound (II) can be obtained in the following manner. 
wherein R2, R3, R4 and X are as defined above, R7 is a thiol-protecting group and R8 is an amino-protecting group.
Compound (VII) can be obtained by removing R8, which is an amino-protecting group of compound (IX) disclosed in Japanese Patent Unexamined Publication No. 233076/1985 and the like, by a method known per se to give compound (X), reacting compound (X) and compound (V) in the same manner as in Production Method 2 to give compound (XI), and removing R7, which is a thiol-protecting group by a method known per se. As the thiol- and amino-protecting groups, the protecting groups generally known in the pertinent field can be used. 
Wherein R2, R3,R4 R5 and X are as defined above.
Compound (II) can be obtained by reacting compound (VIII) disclosed in Japanese Patent Unexamined Publication No. 233076/1985 and the like, and compound (V) in the same manner as in Production Method 2.
Where necessary, the carbapenem compound (II) thus obtained can be converted to a carboxylic acid derivative wherein R5 is hydrogen atom by removing carboxyl-protecting group, according to a conventional method. While the method for the removal of a protecting group varies depending on the kind thereof, a method generally known in this field can be used.
The carbapenem compound (I) and carbapenem compound (II) can be purified as necessary according to a conventional method, such as recrystallization, preparative thin layer chromatography, column chromatography and the like. Alternatively, it can be purified as salts thereof, where necessary.
The carbapenem compound (I) and carbapenem compound (II) can be converted to a pharmaceutically acceptable salt thereof by a method known per se.
The objective compound (I) and compound (II) of the present invention preferably have a configuration of compound (Ia) and compound (IIb) below. 
wherein R1, R2, R3 and R4 are as defined above. 
wherein R2, R3, R4 and R5 are as defined above.
The carbapenem compound (I) and a pharmaceutically acceptable salt thereof are promptly absorbed in blood by oral administration, and metabolized into a carbapenem compound of the formula (I) wherein R1 and R2 are hydrogen atom, or a pharmaceutically acceptable salt thereof, and show high concentration in blood.
In addition, carbapenem compound (I) upon conversion into a pharmaceutically acceptable salt thereof shows enhanced solubility in the digestive tract, which in turn further improves absorption effect, and thus, absorption property.
Therefore, an agent for the prophylaxis and treatment of infectious diseases comprising carbapenem compound (I) or a pharmaceutically acceptable salt thereof shows superior action by oral administration as mentioned above, and can be generally administered as an oral preparation.
This agent for the prophylaxis and treatment of infectious diseases can be produced by diluting the compound with pharmaceutical excipients by a method known per se. Examples of usable excipient include starch, lactose, sugar, calcium carbonate, calcium phosphate and the like.
Moreover, this agent for the prophylaxis and treatment of infectious diseases preferably contains an organic acid, whereby carbapenem compound (I) and a pharmaceutically acceptable salt thereof are caused to have higher solubility in the digestive tract, thus facilitating absorption thereof into blood.
The organic acid may be any as long as it is pharmaceutically acceptable, and is preferably exemplified by organic carboxylic acids such as maleic acid, fumaric acid, tartaric acid, citric acid, succinic acid, malic acid, oxalic acid, mandelic acid, malonic acid, benzoic acid and the like. The organic acid is generally added in an amount of 0.01-20 moles, preferably 0.02-2 moles, per mole of carbapenem compound (I) or a pharmaceutically acceptable salt thereof.
Further, this agent for the prophylaxis and treatment of infectious diseases may contain other additives on demand, such as binders (e.g., starch, gum arabic, carboxymethylcellulose, hydroxypropylcellulose, crystalline cellulose and the like), lubricants (e.g., magnesium stearate, talc and the like), disintegrators (e.g., carboxymethylcellulose calcium, talc and the like), and the like. After adding various ingredients, the obtained mixture is formulated into a dosage form suitable for oral administration, such as capsules, tablets, fine granules, granules, dry syrups and the like, by a method known per se to give an agent for oral administration, which is for the prophylaxis and treatment of infectious diseases.
While the dose of carbapenem compound (I) and a pharmaceutically acceptable salt thereof varies depending on the administration target, symptom, and others, when, for example, the compound is administered to treat suppurative diseases of an adult, the daily dose is about 1-40 mg/kg body weight, which is orally administered 1 to 4 times a day.
Said carbapenem compound (I) and a pharmaceutically acceptable salt thereof may be administered in combination with other antibacterial substance, such as antibacterial drugs (e.g., penicillins, aminoglycosides, cephalosporins and the like) or a therapeutic agent for systemic symptoms caused by bacterial infection (e.g., antipyretic, analgesic, antiinflammatory drug and the like).
The properties and production methods of the compounds of the present invention are explained by way of Examples, to which the present invention is not limited.